Work illuminating tool handle



1950 w. e. KLEINSCHMIDT 2,525,414

WORK ILLUMINATING TOOL HANDLE -Filed June 15, 1946 z; a L

1N VEN TOR.

Arr-arms v:

Patented Oct. 10,

UNITED STATES PATENT OFFICE 2,525,414 WORK ILLUMINATING TOOL HANDLEWillard G. Kleinschmidt, Milwaukee, Wis. Application June 15, 1946,Serial No. 676,876-

1 Claim.

This invention relates to an improvement in work illuminating toolhandles.

It is a primary object of the invention to provide means whereby a welldefined spot of light may be delivered from a tool handle to a workingsurface therebeneath without obstruction by shadows caused by the meansused to support the tool from the handle.

Another object of the invention is to provide a novel and improved toolsuch as a screw driver or the like having an easily controlled source ofillumination built into a handle which is an electrical non-conductor oftransparent material, preferably a plastic.

In the drawings:

Fig. l is a view in longitudinal section through a screw driver handleembodying the invention.

Fig. 2 is a view of the complete screw driver in side elevation.

Fig. 3 is a view in side elevation showing the removable light andbattery assembly.

Fig. 4 is a fragmentary detail view in perspective showing a screw and afragment of a screw driver and illustrating the manner in which the workis illuminated by a screw driver handle made in accordance with thepresent invention.

Fig. 5 is a fragmentary detail view in section similar to Fig. 1 showinga modified embodiment of the invention.

While the invention is applicable to a wide variety of tools, it isparticularly serviceable as applied to the handle 5 of a screw driver 6,preferably having a knurled shank at l engaged in the handle. V

The handle 5 comprises a transparent body of glass or clear plastic suchas polystyrene, a suitable phenolic material, or methy1 methacrylate,for example. Within the handle is a centrally disposed, conicallytapered surface 8 at the end of a light chamber 9 in which the lamp inis positioned. In practice, I have found it desirable that the taper ofthe conical surface 8 should be of the order of approximately 21 withreference to a transverse plane normal to the axis of the handle. It ispossible to vary the angularity of a few degrees plus or minus, but Ihave found that if the taper is as much as 30 the light will emerge fromthe side of the handle rather than the end thereof.

While it is broadly unimportant how the lamp it is mounted, I have foundit desirable to mount the lamp by means of a socket shell I I into whichit is threaded. The socket shell is mounted in a carrier l2 seatedagainst the shoulder it at the end of chamber 9. The carrier [2 andshell ll are preferably made of electrically conductive material.

The counterbore I4 is sufficiently larger than the dry cell battery l5to accommodate a light compression spring it, the end of which is coiledabout the battery and the opposite end of which is engaged in the groovei! in the lamp carrier 52.. The bias of this spring normally serves tokeep the battery contact I8 and the central light contact l9 separated.However, the closure 20 which is screwthreaded into the rear end of thehandle, and socketed at 2| to receive the end of the battery, may berotated to advance the battery axially until its contactv l8 engages thelamp contact l9, thereby completing a circuit to the lamp l0, andreturning to the battery through the shell I l, carrier l2 and springl6.

Where it is desired that the plug at the end of the handle be seatedfirmly to take pressure of the operators palm, theplug 2!! may be usedas shown in Fig. 5, such plug being shouldered to engage the end of thehandle body 5. For moving the battery into operative contact ,with thelamp terminal against the compression of the spring IS, a separate screw21 having a knurled end 28 disposed in a recess 29 of the handle may beemployed. The screw preferably has an enlarged head 39 engaged with thebottom of the battery. Since the plug '20 is-not concerned either withlight transmission or electrical conductivity, it may be made of metal,if

desired.

In either construction, removal of the plug 20 or 20' permits thebattery and the spring and the carrier l2 and the lamp to be removed asa unit from the cavity in the handle. The connection of the spring aboutthe battery facilitates such removal and is therefore preferred to anyother means of completing the return side of the circuit. The spring E5is contractile about the zinc or other metallic case which forms theouter electrode of the dry cell l5. It holds securely against therelative axial displacement but permits the ready release of'the batteryfor replacement purposes when the battery is retated with respect to thespring. In both constructions, the movement of the battery as a wholeserves as a switch, the battery being moved by the compression springiii in an outward or switch opening direction and. being moved by theplug 20 or the set screw 2'! in a circuit closing direction.

The purpose and effect of the conically tapered surface at 8 is tofunction like the surface of a lens or circular prism to throw outwardlythe light from lamp In which would otherwise encounter the end of theshank of the tool. By reason of this bevel, the light enters the plasticcomposition of the handle in the form of a cone, the light diverginguntil it strikes the tapered surface 25. In practice, this surface hasan angle of approximately 8 or 9 degrees inwardly from the grip portionof the handle. In any event, the angularity of the surface 25 should bebelow the socalled critical angle at which the light would emergelaterally from the handle. Thus, the light will be confined in theplastic instead of emerging therefrom.

Surrounding the tool 6 is a bevel 26 which, in practice, has an angle ofapproximately 60 from a transverse plane normal to the aXis of thehandle and tool. With the other proportions 'substantially as indicatedin the drawing, it is found that the light of lamp 9 will almostentirely emerge through the beveled surface 26 and will passconvergingly toward the work surface at which the tool is to be used,thus creating'a well defined and relatively brilliant spot ofconcentrated light immediately around the end of the tool when the lampI is energized.

This result is achieved by reason of the fact that the light istransmitted through handle portions which provide a path ofapproximately uniform length and within which the light is confined andguided and concentrated for delivery to the surface 8, the taper of thehandle at 25 being insufficient to permit the light to escape. Since theportions of the handle which pipe the light to the delivery surface arethe same portions which provide mechanical support for the tool, asrepresented by screw driver 6, it will be apparent that no shadow iscast.

For different lengths of tool shank, different angles of light receivingand light emitting surfaces may have to be employed to focus the lighton the work as desired. The principles involved are well known to thoseskilled in optics and the angles specified are given merely by way ofexample of one operative arrangement. In the device using the anglesspecified, the total width of the light receiving bevel is A; inch,while the total diameter of the lamp chamber 9 is g2 of an inch. Thelight receiving bevel 8 is spaced 1%; inches from the socket in whichthe tool shank is disposed. The overall diameter of the handle is 1inch. The length of its tapered portion 25 is 1 inch and a quarter andthe diameter of the conical light emitting surface 26 is of an inch. Thetool shank socket happens to be of an inch.

As above noted, total refraction is achieved in this arrangement andsubstantially all of the light of the lamp is concentrated in a spot atthe workin zone at the operative end of the tool.

I claim:

In a lamp-illuminated tool handle for a tool such as a screw driverprovided with a shank, a light transmitting body of generally circularform in cross section having an axial tool-shank receiving bore, saidbody being provided in axial alignment with said bore with a conicallight receiving surface of approximately a 21 angle with respect to aplane normal to the handle axis, the said surface being disposed inimmediate proximity to the said lamp to receive light therefrom and t0refract the light rays within said body, the said body also beingprovided around said bore with an annular frusto-conical surface at anangle not to exceed approximately from a transverse plane normal to theaxis of the handle and tool, said surface refracting and directing lightrays emanating from said body convergently along said axis, the wall ofsaid bore closely engaging the shank of the tool throughout the portionof the tool received in said bore, the surface of the body disposedbetween said conical light-receiving surface and said firstmentionedannular frusto-conical surface being annular and frusto-conical andtapering inwardly toward the first-mentioned frusto-conical surface atan angle less than that at which light would emerge laterally from thesaid last-mentioned frusto-conical surface of the body.

WILLARD G. KLEIN SCHMIDT.

REFERENCES CITED The following references are of record in the file ofthis patent;

UNITED STATES PATENTS

